Microphase separated block copolymers (BCPs) offer unique opportunities to control the spatial distribution of nanoparticles, opening pathways to improve the mechanical strength, conductivity, permeability, catalytic activity, and optical and magnetic properties of thin films See, for example, Jaramillo, T. F.; Baeck, S. H.; Cuenya, B. R.; McFarland, E. W. J. Am. Chem. Soc. 2003, 125, 7148; Feldheim, D. L.; Grabar, K. C.; Natan, M. J.; Mallouk, T. E. J. Am. Chem. Soc. 1996, 118, 7640; Honda, K.; Rao, T. N.; Tryk, D. A.; Fujishima, A.; Watanabe, M.; Yasui, K.; Masuda, H. J. Electrochem. Soc. 2001, 148, A668; Bockstaller, M. R.; Mickiewicz, R. A.; Thomas, E. L. Adv. Mater. 2005, 17, 1331; and Fan, H. J.; Werner, P.; Zacharias, M. Small 2006, 2, 700. The ability to control the orientation and lateral ordering of BCP morphologies makes BCPs particularly attractive as scaffolds and templates for the fabrication of nanostructured materials. See, for example, Haryono, A.; Binder, W. H. Small 2006, 2, 600; Black, C. T.; Murray, C. B.; Sandstrom, R. L.; Sun, S. Science 2000, 290, 1131; Thurn-Albrecht, T.; Schotter, J.; Kastle, G. A.; Emley, N.; Shibauchi, T.; Krusin-Elbaum, L.; Guarini, K.; Black, C. T.; Tuominen, M. T.; Russell, T. P. Science 2000, 290, 2126; and Lopes, W. A.; Jaeger, H. M. Nature 2001, 414, 735. Several methods for incorporating inorganic nanoparticles into polymeric nanostructures have been described. In one, nanoparticles are generated within block copolymer micelles, where metal nanoparticles can be produced by simple chemical methods. See, for example, Cheng, G.; Moskovits, M. Adv. Mater. 2002, 14, 1567; Gorzolnik, B.; Mela, P.; Moeller, M. Nanotechnology 2006, 17, 5027; and Sohn, B.-H.; Choi, J.-M.; Yoo, S. I.; Yun, S.-H.; Zin, W.-C.; Jung, J. C.; Kanehara, M.; Hirata, T.; Teranishi, T. J. Am. Soc. Chem. 2003, 125, 6368. In another, the cooperative self-organization of nanoparticles and block copolymers is used with the need of subsequent chemistry. See, for example, Lopes, W. A.; Jaeger, H. M. Nature 2001, 414, 735; (13) Thompson, R. B.; Ginzburg, V. V.; Matsen, M. W.; Balazs, A. C. Science 2001, 292, 2469; Hamley, I. W. Angew. Chem. Int. Ed. 2003, 42, 1692; Chiu, J. J.; Kim, B. J.; Kramer, E. J.; Pine, D. J. J. Am. Soc. Chem. 2005, 127, 5036; Kim, B. J.; Chiu, J. J.; Yi, G.; Pine, D. J.; Kramer, E. J. Adv. Mater. 2005, 17, 2618; Lin, Y.; Böker, A.; He, J.; Sill, K.; Xiang, H.; Abetz, C.; Li, X.; Wang, J.; Emrick, T.; Long, S.; Wang, Q.; Balazs, A.; Russell, T. P. Nature 2005, 434, 55; Ansari, I. A.; Hamley, I. W. J. Mater. Chem. 2003, 13, 2412.
The surface reconstruction of BCPs, as reported previously, is another method to this end. See, for example, Xu, T.; Stevens, J.; Villa, J.; Goldbach, J. T.; Guarini, K. W.; Black, C. T.; Hawker, C. J.; Russell, T. P. Adv. Funct. Mater. 2003, 13, 698; Park, S.; Wang, J.-Y.; Kim, B.; Chen, W.; Russell, T. P. Macromolecules 2007, 40, 9059; and Park, S.; Kim, B.; Wang, J.-Y.; Russell, T. P. Adv. Mater. 2008, 20, 681. Surface reconstruction is a process where, in the case of a diblock copolymer with cylindrical microdomains oriented normal to the surface, upon exposure of the BCP film to a solvent that preferentially dissolves the minor component block, the minor component is drawn to the surface of the film, and, upon drying, cylindrical nanopores are produced with dimensions comparable to the original cylindrical microdomains. The minor component block fully coats the surface of the nanoporous film and, as shown by grazing incidence x-ray scattering, if the film thickness is a period of the BCP or less, the nanopores were found to span the film and had vertical side walls. Since the solvent does not alter the chemical structure of the BCP, the reconstruction is fully reversible. So, by heating the film to near its glass-transition temperature, Tg, a full recovery of the initial thin film morphology occurs. However, if the BCP film is heated to temperatures well in excess of Tg, then interfacial interactions will control the orientation of the microdomains. If, prior to heating, metal is evaporated at a glancing angle onto the surface of the reconstructed film, a porous metal film is obtained. In most pattern transfer approaches, a nanoporous polymer template has been used to transfer a pattern into underlying substrates using RIE and/or milling (see, for example, Park, M.; Chaikin, P. M.; Register, R. A.; Adamson, D. H. Appl. Phys. Lett. 2001, 79, 257; Cheng, J. Y.; Ross, C. A.; Thomas, E. L.; Smith, H. I.; Vancso, G. J. Appl. Phys. Lett. 2002, 81, 3657; Meli, M.-V.; Badia, A.; Grütter, P.; Lennox, R. B. Nano. Lett. 2002, 2, 131); Guarini, K. W.; Black, C. T.; Zhang, Y.; Kim, H.; Sikorski, E. M.; Babich, I. V. J. Vac. Sci. Technol. B 2002, 20, 2788; and Kubo, T.; Parker, J. S.; Hillmyer, M. A.; Leighton, C. Appl. Phys. Lett. 2007, 90, 233113), while the control of spatial location of metal on polymer template can be used as etching masks for preparation of various kinds of nanostructured patterns.